Computing gun sight



Dec. 11, 1951 F. A. LYON COMPUTING GUN SIGHT 7 Sheets-Sheet 1 Filed July 28, 1944 INVENTOR FLOYD A.

/ ATTORNEY.

Dec. 11, 1951 7 Sheets-Sheet 2 Filed July 28, 1944 FIG.2

INVENTOR FLOYD A. LY N mama mm Dec. 11, 1951 F. A. LYON 2,577,785

COMPUTING GUN SIGHT Filed July 28, 1944 '7 Sheets-Sheet 3 -|NVENTOR FLOYD A. LYON Dec. 11, 1951 F. A. LYON 2,577,785

COMPUTING GUN SIGHT Filed July 28, 1944 7 Sheets-Sheet 4 F|G.5 FIG.6 U i a I v A II/II/IIIIIIIIIIIIIIII/l 41 l? l N V E N TO R F LO Y o A. LYO N ATT-OR Dec. 11, 1951 F. A. LYON 2,577,785

COMPUTING GUN SIGHT Filed July 28, 1944 7 Sheets-Sheet 5 FIGS FIG-8 F'IG.7

INVENTOR FLOYD A. LYO

Dec. 11, 1951 Filed July 28, 1944 F. A. LYON 2,577,785

COMPUTING GUN SIGHT '7 Sheets-Sheet 6 FIG.IO

INVENTOR FLOYD A. LYON TTORNEY Dec, 11, 1951 F, A LYON 2,577,785

COMPUTING GUN SIGHT Filed July 28, 1944 7 Sheets-Sheet '7 FIG-l2 MULTIPLYING LINK cos. G.E. Fl G. l3 rW INPUT 6.5. SCOTCH YOKE T INPUT c.A (LBD+LPD) f PREDICTION LOGHALTH LOG (|A$ Eymmsng 34 I75 435 FIG.I4 L 5 1,

'INVENTOR FLOYD A. LYON Patented Dec. 11, 1951 COMPUTING GUN SIGHT Floyd Lyon, Elmhurst, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application July 28, 1944, Serial No. 547,055

8 Claims. (Cl. 33-49) This invention relates to a computing sight and more particularly to gun sights of the kind in which the line of sight defining means is automatically displaced with respect to the bore of the gun during target tracking operations according to prediction angles computed by the sight mechanism.

An object of the invention is the provision of a more accurate sight at reduced cost, size and weight.

Another object is the provision of a compact computing and sighting unit which may be attached easily to existing turret gun installations without appreciably crowding the turret.

' A further object of the invention is to provide a sight having a simplified mechanism designed to make maximum use of die-cast parts thereby reducing the manufacturing cost of the device and accelerating production.

A still further object is to provide a sight composed of a number of independently assembled units so designed as to be interconnected easily in final assembly without the need for further machining or adjustment.

Other objects of the invention will appear in the following description given with the aid of the accompanying drawings, of which:

Fig. 1 is a schematic drawing of the sight mechanism;

Fig. 2 is a plan view of the computing mechanism partly in section as it appears when the cover of the enclosing casing is removed;

Fig. 3 is a vertical section taken through 3-3 of Fig. 2;

Fig. 4 is a vertical section taken through 44 of Fig. 2;

Fig. 5 shows a variable speed drive unit in transverse section;

Fig. 6 shows the variable speed drive unit in section, the section being taken through 6-6 of Fig. 5;

Fig. 7 shows the variable size reticle mechanism on an enlarged scale;

Figs. 8 and 9 show details in plan and section, respectively, of a variable speed mechanism;

Fig. 10 is a view of the sight in elevation; and

Figs. 11, 12, 13 and 14 are diagrams illustratin respectively, the range finder, multiplying linkage, azimuth input mechanism, and adding linkage.

The mechanism of the sight is enclosed in a casing for mounting on any suitable support which will permit the sight to be moved for target tracking purposes. It will be understood that the sight may be used in the known manner for the remote control of a gun. Due to its small size, however, the sight may be directly mounted by means of a suitable adapter on the guns in any existing turret, and the description of sight will be directed to the arrangement whereby the sight is mounted on, or between a pair of guns, the computing mechanism of the sight being driven by the movements of the gun or a gun turret in elevation and azimuth.

Known computing sights have utilized data obtained from movements of the gun in various ways in combination with various ballistic functions to obtain desired prediction angles. Generally speaking, former structures having comparable accuracy were heavy and bulky consisting of numerous cams, differentials and variable speed units, all of which were of precision construction, expensive and slow to manufacture and assemble. Due to the novel construction of the sight of the present invention only three threedimension cams, two differential units and three variable speed drives are required, in addition to some intermediate mechanism consisting principally of levers, yet the sight automatically calculates ballistic deflections corrected for range, ind ma tj agspeeialtitude, gun azimuth and gun elevation. The time of flight, which is used for prediction, is corrected for range and altitude.

The casing which encloses the sight mechanism has a number of irregularly shaped castings attached thereto provided with bearings of various kinds for the respective units of the sight mechanism which will be referred to as the description of the device progresses.

During a target tracking operation the motion of the gun or turret is transmitted to the sight in any convenient manner. In Fig. 1 an azimuth gear 2| attachedto the gun or turret drives a gear 22 of a flexible cable 23 connected by shaft 24 to gear 25 shown also in Fig. 2 inside sight casing 20. Gear 25 drives gear 26 connected by shaft 21 to gear 28 coupled by shaft 29 to worm 30 which drives worm gear 3| connected by shaft 32 to long pinion 33 meshed with gear 34 for rotating three dimension cam I in proportion to the angular rate of the gun in azimuth. This cam will be referred to again further on,

Gear 28 drives gear 35 of a variable speed device 36 shown also in Figs. 2, 5 and 6. The parts of the variable speed device are supported by an independent framework 40 so designed that it may be inserted into the machine as a unit and coupled with the rest of the mechanism without altering the position of interconnecting members. This arrangement provides a more compact structure and simplifies assembling of the device.

Gear 35 is formed integrally with disc 38 of the constant speed device and its shaft 39 turns in a bearing in the framework 40. A horizontal shaft 4I secured between opposite sides of framework supports for sliding movement the bifurcated arms 42 of a ball carriage which carries a pair of balls 43 disposed between disc 38 and a roller 44 supported by bearings in opposite sides of framework 40. A shaft 45 attached to the roller and projecting through the frame carries a gear 46 that drives one arm of a differential unit 31, Fig. 1, which will be described further on. A spring 47 and an adjustment screw 48 therefor are provided to maintain pressure between the roller, balls and disc in the usual manner. The ball carriage is displaced in the known manner in proportion to the cosine of the gun elevation angle rate (cos GE) to convert azimuth velocity, to velocity in a slant plane, by a crank 49, having an arm positioned between the arms 42 of the ball carriage. The crank is mounted on shaft I I driven from the elevation input mechanism described below, by gears I2 and I3, shaft I4, the latter carrying gear I in mesh with the long pinion 13 of the gun elevation input mechanism. The output of the variable speed unit is a diplacement of shaft 45 proportional to the product of the gun azimuth rate GA and cos GE which is the displacement of the line of sight in a plant plane.

The gun or gun turret movement in elevation may be communicated to the sight in any desired manner, the usual arrangement, shown in Fig. 1, consists of a sector 59 which drives a ear connected by a flexible shaft 5I, and a shaft 52 to gear 53 inside of the sight casing. Gear 53 is the input for an elevation gear unit, Fig. 2, which consists of a supporting casting having a base 54 on which is formed a number of upright members provided with bearings for several shafts. The unit is so arranged that the gears and shafts may be separately assembled thereon and the whole assembly thereafter inserted into the easing, the respective driving and driven members of the unit fitting in with other interconnecting members without adjustment.

Gear 53 is in mesh with a gear 55 secured to shaft 56 supported in a bearing in upright member 51 of the elevation input unit casting. Shaft 56 through bevel gears 58 and 59 drives a shaft 60 carrying a gear 6I which meshes with an input gear of a differential 66. Gear 62 on shaft 60 drives gear 63 and shaft 64 which turns a gun elevation dial 65 that can be observed through a window in the front of the case as shown in Fig. 10.

Shaft 56 also carries a gear III which through gear II and shaft I2 drives a long pinion I3 that turns elevation ballistic cam II by means of gear 14 formed at the end of the cam.

Gear 46 of the azimuth mechanism and gear SI of the elevation mechanism as already decribed each drive an input member of an individual equating differential. These differentials 31 and 66 are parts of the respective constant speed drive rate equating mechanisms I9 and 80 which are alike except that they bear right and left hand relationship to each other. The mechanisms are used for computing prediction angle rates.

In Fig. 1 unit I9 associated with gun azimuth (shown near the top of the sheet) is represented as being partially enclosed in a framework while the corresponding unit 80 associated with gun elevation is shown with the framework omitted to give a better understanding of the device. Figs. 8 and 9 show details of the mechanism of the multiplier unit I9. Each unit I9 and comprises a differential supported by an arm BI and the frame 82. Gear 83 of the differential 31 is driven by gear 46, while gear 6I on the other side of the machine drives the corresponding element of the differential 66 for rate equating member 80. Associated with each differential, is a clutch controlled by member 84 operated by known means which are not part of the present invention for disconnecting the sight mechanism according to known practice, when the gun position is being rapidly shifted. The clutch is indicated by spring 85 and friction disc 86.

Referring to Fig. 1, the shafts 81 of the differentials are connected to the associated drum 88 of the variable speed device rotated by balls 89 of a ball carriage which are driven by disc 90 coupled to gear 9I driven at a constant speed by constant speed motor 92. Gears 9I of the respective units are driven from the constant speed motor by a gear and cross shaft mechanism including gear 93 on the motor shaft which drives gear 94, shaft 95, meshed gears 95 and 91, shaft 98, gears 99 and I00, shaft II, and finally gear I92 which is in mesh with gear 9I.

The ball carriages of the units I9 and 80 are displaced by a bell crank and lever mechanism positioned variably from shaft III) of the differential in accordance with the position of fulcrum studs I09 carried by a framework which supports a range cam III. The framework moves with the range cam in translation and positions the fulcrums accordingly in a horizontal plane, the variably positioned fulcrums being used to introduce a time of flight function of range into the respective multipliers to delay the action thereof for the purpose of stabilizing the sight to prevent too great an initial offset to the optics when the sight is rapidly slewed in overtaking a target. The time lag does not affect the magnitude of the prediction deflection. Irrespective of the position of the variable pivot I09, it will require a certain ball carriage displacement to equate the gun elevation (GE) rate or the gun azimuth X cosine gun elevation rate (GA cos GE). The speed of equating these rates, however, will be inversely proportional to time of flight.

Output shaft III] of the differential turns in a bearing in framework 82 for the constant speed multiplier and inside of the casing framework, Fig. 8, the shaft carries a gear H2, Fig. 1, in mesh with rack H3 supported by members H4 and H5 which slide on a vertical member H6 supported by the framework of the unit. The rack is connected with a pin III that projects outward through a slot in the framework where it is pivoted'into the end of lever H8 of a multiplying linkage. The opposite end of lever H8 is supported by a pin H9 projecting into an open slot I20 formed therein. The fulcrum of lever H8 is stud I99 carried by the range cam framework. Pin I I 9 is supported at the end of a second lever I22 secured to a shaft I23 so that the shaft turns with the lever. Shaft I23 is pivoted in a bearing in the framework of the unit and its inner end carries a depending bifurcated member I24 which turns with the shaft. The depending arms of member I24 engage opposite ends of a ball carriage for balls 89, the coupled arrangement of lever I22, shaft I23 andebifurcated member I24 being equivalent mechanically to a bell crank which is used to move the ball carriage.

amines Lever I22 engages the upper end of a pin I25 supported for vertical reciprocation in a bearing formed on the outside of framework 82. The lower end of the pin imparts the movement of lever I22 to an adding linkage. This movement represents the lateral or vertical prediction rates computed by the respective multiplying mechanisms.

In operation, the input drive from either gear 46 or 6I of the respective multipliers displaces the associated shaft H and rack II3. Lever H8 is rocked on its fulcrum stud I09 which is displaced with rangecam III along a horizontal plane as a time of flight function of range. The movement of the lever is communicated to the bell crank arm I24 which displaces the ball carriage along driving drum 88 which turns an input gear of the differential until the ball carriage is displaced to a position of equilibrium where the rate input from the turret in gun elevation or gun azimuth is balanced with that of the drum. This displacement as already described is communicated to pin I25 and the adding linkage. The displacement of the pin I25 associated with unit 80 represents a vertical prediction deflection divided by a function of the time of flight, while that of the pin I 25 of multiplier 19 represents a lateral prediction deflection divided by a function of the time of flight as will be explained in greater detail later on.

In Fig. 10 portions of three knurled discs are shown partly projecting through the sight casing. These discs are conveniently located so that they can be turned by the thumbs of an operator. Discs I30 and I 3| are used respectively for setting target dimensions and indicated air speed into the sight mechanism. Disc I32 is used to adjust the mechanism for altitude.

Disc I32 is shown in Fig. 1 coupled to a gear I33 in mesh with an idler gear I34 which turns a ring I35 carrying a lubber line I36 that cooperates with a stationary scale I31 having graduations which represent the altitude factor function on a logarithmic scale. The lubber line is positioned by disc I32 in alignment with the altitude value of scale I31. Ring I35 is coupled by link I38 to a similar ring I40 carrying lubber line I for the target dimension scale. Movement of ring I 35 effects through the link a similar movement of ring I40.

Indicated air speed disc I3I is secured to a gear I42 which meshes with a gear I43, Fig. 2, on shaft I45 that turns IAS dial I46 associated with ring I35 and lubber line I36. Dial I46 is graduated to represent the IAS factor function on a logarithmic scale. Disc I3I is adjusted to align the appropriate air speed value of dial I46 with the lubber line.

Gear I46 on shaft I45, Figs. 1, 3 and 4, turns a lead screw I41 by means of gear I48, shaft I49, gears I50 and II.

The lead screw translates ballistic cam I by means of fork I52 which engages a flange at the end of the cam. The cam is moved in rotation by long pinion 33 driven from the azimuth input mechanism as already mentioned.

The group of gears and shafts just described are assembled as a single unit in a casting I53 provided with suitable bearings for the shafts.

Pinion 33 turns gear I55 on shaft I56 carrying gun azimuth dial I51 which may be seen through a window in the front of the sight casing.

Target dimension adjustment disc I30, by means of gears I50 and I59, turns a shaft I60, Figs. 1 and 2, carrying a target dimension dial I6I in order to position the dial with respect to lubber line MI. The dial graduations give target dimensions directly on a logarithmic scale.

Shaft IE0 is used also to rotate a three-dimensional range cam III. The shaft carries a gear I62 meshing with a gear I63 on shaft I64, shown as a broken shaft in Fig. 1 extending to the gear of the mechanism where it supports a long pinion I65 in mesh with a gear I66 formed on range cam III, which will be described further on.

The ballistic correction computing mechanism which includes three-dimensional cams I and II solves the ballistic corrections in elevation and azimuth. The output of the ballistic mechanism is a displacement proportional to the ballistic correction per unit of time of flight, for example, angular mils per second of time of flight.

Ballistic cam I is mounted for translation on a shaft I10, Fig. 3, supported in bearings in castings III and I12. The lift pin I13 for the cam is mounted underneath the cam in a bearing formed in a web connecting the castings just mentioned. The pin engages one end of a lever I14 of a differential adding linkage, the other end of the lever being operated by pin I25 of unit 19 as already described.

Lever I14 is pivoted to the lower end of a vertical rod I15 arranged to reciprocate in a bearing in casting I12. The rod is urged upward by spring I16 whereby the ends of lever I14 are kept in contact with lift pin I13 and pin I25.

The upper end of rod I15 is attached by pivot I11 to a lever I18 which has a shiftable fulcrum I19 formed by stud carried by an extension of the movable framework supporting the range cam.

The free end of lever I18 engages a vertical rod I supported for endwise movement in a bearing in a casting I8I which supports an assembly of members for adjusting the sight optics. Rod I80 adjusts the lateral deflecting mirror of the sight.

The ballistic mechanism is preferably proportioned to compute ballistic correction on the basis of the following equations representing ballistic deflections, derived from a study of ballistic tables.

LBD=lateral ballistic deflection VBD=vertical ballistic deflection K1=basic constant deflection when altitude is 40,000 ft., IAS is M. P. H., if is 1 sec. and sin GA is 1.

f (alt) =altitude factor which is a funtion of altitude f(IAS) =indicated air speed factor which is a function of IAS.

tr=time of flight of the bullet and is a function of range and altitude.

Kz=basic gravity deflection constant when tr is 1 sec. and cos GE=1.

GA=gun azimuth angle.

GE=gun elevation angle.

The azimuth ballistic cam I solves Equation 1 as follows:

The cam is translated by the IAS knob rotation and rotated by the gun azimuth angle (GA) input. Rotation of the IAS knob I3I is setting IAS graduation against altitude lubber I36 which has previously been set to altitude represents:

log Halt) +10: flIAS) 7 which is similar to multiplying by the slide rule method. Cam I is made to a logarithmic curve in translation designed to de-log the above function. The cam is designed to give K1 sine gun azimuth angle (GA) in rotation. The resultant lift of the cam pin I13 gives The movement of the cam pin I13 effects a corresponding displacement of lever I14 of the addin linkage already described.

Ballistic cam II, Figs. 1 and 4, is translated by lift pin I85 which is operated by cam I. Lift pin I85 is located 90 away from the other lift pin I13 of cam I, and, accordingly, the translation of cam II is similar to that of lift pin I13 except that sin GA is changed by the location of pin I85 to cos GA. The cam is rotated by the gun elevation input mechanism as already described.

Lift pin I86 operated by cam II is disposed underneath the cam, and the lower end thereof engages one end of lever I81 of a differential adding linkage, whose opposite end is engaged by pin I25 of unit 80. The mechanism connected with this lever is similar to that of lever I14. The lever is pivoted to a rod I88 supported for vertical endwise movement. The upper end of the rod is pivoted at I89 to lever I90 having a fulcrum I9I comprising a stud carried by an extension of the movable frame supporting the range cam. Lever I90 operates a rod I92 that controls the optics of the sight to deflect the line of sight in elevation.

Cam II solves Equation 2 as follows: The cam is translated according to LBDXcos GA t Xsin GA and is rotated in proportion to the gun elevation angle (GE). The cam is designed to give lifts proportional to (the product of its translation and sin GE) (K2 cos GE).

The resultant lift of the pin of cam II gives K1 f(alt) X f(IAS) cos GAX sin GEK- X cos GE:

Range cam III is closely associated with the optical system of the sight, so in order to give a clearer understanding of the range cam, the optical system will be described next. The optical system, Fig. 1, is of a known kind consisting of a lamp 200, a reticle 20I, a stationary mirror 202 which reflects beams of light shaped by the reticle onto a lateral deflection mirror 203 which further deflects the rays of light onto a slanting transparent mirror 204 disposed in the line of sight whereby the image of the reticle is superimposed on the target viewed through the transparent mirror 204. A suitable lens 205 is disposed between the reticle and mirror 2021 to focus the reticle light into a parallel beam thereon.

Mirror 203 is secured to a shaft 206 to which is fastened an arm 20! engaged by the upper end of rod I80 which maintains the mirror at the proper lateral deflection angle.

similarly, transparent mirror 204 is mounted on a shaft 208 having an arm 209 fastened thereto engaged by vertical rod I 92, the movement of the rod maintaining the mirror positioned so as to deflect the line of sight according to the vertical deflection angle.

The reticle of the present sight, Fig. '7, comprises two discs, one of which is stationary and the other movable. In the present instance the radial slots while the movable disc has cooperating slots in the form of logarithmic spirals. These discsact as a light gate allowing light to pass through the small rhombi of intersection of radial and spiral slots. The image of these rhombi is focussed by lens 205 of the optical system so they appear on the combining glass 204 as a circle whose circumference is formed by small diamond-shaped beams of light.

The movable plate 2") of the reticle is connected by pin 2 I I to one arm of a lever 2 I 2 pivoted at 2I3. The opposite end of the lever is actuated by lift pin 2 I4 of range cam III.

It will be understood that when the two discs of the reticle are moved with respect to each other, the diameter of the circle of light rays projected through the intersecting slots will vary accordingly. In sighting operations with a sight of this kind, the reticle is adjusted so that it just encloses the target or a part thereof of known dimension, and by so adjusting the reticle, after the target dimensions have been set into the sight, an accurate measure of range is automatically set into the sight mechanism.

In the present embodiment of the invention, the range cam is utilized to adjust the size of the reticle. The range cam is positioned in one dimension according to a time of flight function as will be described in detail.

The range cam III is mounted for rotation within a framework 220, Figs. 2 and 4. Both the framework and the cam are supported for translation on a shaft 22 I, held between upright members 222 and 223 of a casting supporting the assembly. The cam is spaced from the ends of framework 220 by sleeves 224 and 225. A yoke 226, projecting from one side of the framework 220, Fig. 1, whose arms slide on opposite sides of shaft I64 keeps the framework from turning on its supporting shaft.

symmetrically disposed on the framework are four legs 221, 228, 229 and 230, best shown in Fig. 2. Each leg carries a stud already mentioned, which serves as a movable fulcrum for one of the levers of the intermediate mechanism. Stud I19 on leg 221' is the fulcrum for lever I18, Fig. 3; stud I9I on leg 229 is the fulcrum for lever I 90; and a stud I09 on each of the legs 228 and 230 are the fulcruins for levers II8 of variable speed units I9 and 80, respectively.

The range cam has already been described as being rotated by long pinion I65 operated by knurled target dimension disc I30 at the front of the sight casing.

The range cam and its enclosing frame are translated by a range motor 235, Fig. 1. The range is controlled in the known manner by a suitable circuit controlling device capable of causing the motor to start, stop and turn in either direction. A controlling device is indicated as a button located adjacent to a sight handle 231. It will be understood that this device may be of any suitable kind and disposed for foot operation, if so desired. The range motor shaft operates a rack 238 formed integrally with the frame of the range cam through a train of reduction gears consisting of gear 239 on the motor shaft, idler gear 240, gear I, worm 242, worm gear 243 and gear 244, the latter being in mesh with rack 238. As the range decreases, the range cam, as shown in Fig. 1, is translated toward the left of the drawing, increasing the elevation of the lift pin which effects a corresponding increase in the diameter of the reticle. A dial 232 mounted on stationary disc is provided with a number of shaft 233 driven by gear 234 and a rack on the side of the cam framework provides a range indicator which may be observed from the top of the sight casing.

The range mechanism solves range by triangulation in the known manner as illustrated by the diagram shown in Fig. 11, where TD T where f=the focal length of lens cl=reticle diameter TD=target dimension R=present range The range cam is translated in order to adjust the reticle diameter it so that the above equation is satisfied. For a given rotation of cam III, d is inversely proportional to range. The cam solves an equation of t; as a function of range as will be described. The translation of the cam required to position the reticle represents a function of if. The cam is designed to de-log the TD input in rotation.

The time of flight correction for altitude As altitude increases, air density decreases, the less dense air offering less resistance to the projectiles. Therefore it is desirable that the time of flight be corrected for altitude.

Time of flight is given empirically by t =.109 (R/100) +.00192 (R/100) at an altitude of 18,350 ft. density ratio=.5732. Time of flight may be given approximately for any altitude by using a false range R which is given by where Ft fllll.) is a time of flight factor of altitude and is a function of f (alt) the altitude factor used for the altitude dial graduations. The Ft (alt) is introduced by a linkage connecting the altitude lubber line to the TD lubber line as a logarithmic function. The altitude lubber setting gives log f(alt). The linkage is designed to position the TD lubber as log Ft mlt). The TD dial is graduated as log TD. The altitude setting positions the TD lubber as log Ft (alt). When the TD dial setting is made the rotation thereof represents log TD+log Ft (alt) according to the slide rule method of multiplication. The range cam is designed to de-log the rotation input. Upon de-logging, the input function to the cam represents.

Ft mm XTD Using this value of false TD in the solving for false range 10 ing the range cam. This arrangement is believed to be new.

The prediction solution of the sight is obtained by equating the gun rate with the variable speed drives and their associated difierentials.

Figures 12 and 13 are diagrams which illustrate respectively the operation of the elevation and azimuth prediction mechanism.

The desired prediction solution is given by the differential equations VPD +5 (VPD) L E dt G'A COS The variable fulcrum I09 is displaced with the range cam according to t the lever connections being such as to cause the bellcrank arrangement I22-I24 to be rocked by multiplying lever H8 in inverse proportion to the time of flight. The ball carriage displacement accordingly is inversely proportional to the time of flight, while the movement of pin I25 represents the prediction rate replaced by LPD The displacement of the lift pin I13 of cam I represents LBD f or the lateral ballistic correction per unit of time and, as already stated, that of pin I 25 represents LBD The displacements of the pins are added by lever I14, as shown in the diagram of Fig. 14, their sum appearing as the resulting displacement of the vertical fulcrum pin I15 on which lever I14 is pivoted. In the same way VBD is added to VPD their sum appearing as a displacement of vertical rod I88 to the end of which lever I81 is pivoted. The output of the adding links gives the total lateral or vertical deflections in angular mils per second. In order to obtain the total lateral deflection and the total vertical deflections, these deflections are multiplied by t by means of a second multiplying lever arrangement whose connections are such as to cause the displacement of vertical fulcrum pins 188 or I15 to be multiplied directly by i thereby obtaining the desired total deflection. In Fig. 12, vertical fulcrum pin I88 of adding link I8! is shown as engaging one end of lever I90. The movable fulcrum I! is attached to the range cam framework causes the lever movement to be multiplied directly by time of flight whereby the opposite end of the lever is displaced according to the desired deflection, which is shown as vertical prediction deflection. The arrangement just described wherein the ballistic and prediction functions are first added and then multiplied by time of flight is believed to be novel and results in a considerably simplified mechanism.

The computing sight as described above compntes ihedefle ct igrrs reguired for apifqjectile to strikeg. targeti g g along straight course. If gamma nivmcnlihl tsi ht is installed is attacked by pursuit planes with fixed guns, the attacking craft must fly ahead on curved course which has come to be known as a pursuit curve. Ring I which carries lubber line I36 is provided with an additional attack lubber line l36' so positioned on the ring that when used as a reference, instead of lubber line I36, the time of flight is corrected to apply a correction to the total displacement of the line of sight to compensate for the angular deviation of the pursuit curve.

An important feature of the present invention is that the sight is effective for elevation angles, plus or minus 90 and for 360 in azimuth and therefor may be installed in any gun position of a bomber without alteration of the computing mechanism.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a computing gun sight, means for computing a ballistic deflectionper-unit of time of flight, means for computing the prediction deflection per unit of time of flight, a differential mechanism comprising a lever having a yielding fulcrum, the ends of the lever being disposed so as to be displaced by the respective means in proportion to their computations whereby the fulcrum is displaced according-to the sum of said computations.

2. In a computing gun sight, means for computing a ballistic deflection per unit of time of flight, means for computing the prediction deflection per unit of time of flight, an adding mechanism comprising a lever having a yielding fulcrum, the ends of the lever being disposed so as to be displaced by the respective means in proportion to their computations, the resultin fulcrum displacement being proportional to the sum of said computations, time of flight multiplying means actuated by said fulcrum in proportion to the displacement thereof, the resulting product being a displacement proportional to total deflection.

3. In a computing gun sight, means for computing the elevation ballistic deflection angle per unit of time of flight, means for computing the elevation prediction deflection per unit of time of flight, an adding mechanism comprising a lever having a yielding fulcrum, the ends of the lever being disposed for displacement by the respective means in accordance with their computations, the resulting fulcrum displacement being proportional to the total vertical deflection rate, time of flight multiplying means actuated by said fulcrum in proportion to the displacement thereof, the resulting product being a displacement proportional to total vertical deflection.

4. In a computing gun sight, means for computing the azimuth ballistic deflection per unit of time of flight, means for computing the azimuth deflection per unit of time of flight, an adding mechanism comprising a lever having a yielding fulcrum, the ends of the lever bein disposed for displacement by the respective means in accordance with their computations, the resulting fulcrum displacement being proportional to the total lateral deflection rate, time of flight multiplying means actuated by said fulcrum in proportion to the displacement thereof, the resulting product being a displacement proportional to total lateral deflection.

5. In a computing gun sight, means for computing ballistic deflection per unit of time of flight, means for computing the prediction deflection per unit of time of flight, an adding mechanism having separate inputs individually actuated by the respective means in accordance with their computations, an output member for the adding mechanism, a time of flight multiplying device actuated by the output member, the product obtained thereby being proportional to total deflection, and line of sight defining means deflected by said multiplying device in accordance with said product.

6. In a computing gun sight, means for computing ballistic deflection per unit of time of flight, means for computing the prediction deflection per unit of time of flight, a differential linkage mechanism having separate inputs individually actuated by the respective means in accordance with their computations, an output member for the differential having a displacement proportional to the sum of said computations, a lever having one end actuated by said differential linkage mechanism, a fulcrum therefor movable according to a function of time of flight whereby the opposite end of the lever is displaced according to total deflection.

'7. In a computing gun sight, means for computing ballistic deflection per unit of time of flight, means for computing the prediction deflection per unit of time of flight, a lever disposed on a pivoted fulcrum adapted to be displaced by movements imparted to the lever, means for displacing the ends of the lever by the respective means in proportion to their computations whereby the fulcrum is displacedin accordance with the sum of said computations, a multiplying lever, a fulcrum therefor displaced according to a function of time of flight, said multiplying lever being disposed so that one end thereof is displaced by the first mentioned fulcrum whereby the opposite end of the lever is displaced according to total deflection, line of sight defining means, and a member engaged by the last-mentioned lever for offsetting the line of sight defined by said means according to total deflection.

8. In a computing gun sight, a pair of levers, means for actuating an arm of one of the levers in accordance with the sum of the azimuth ballistic and prediction deflections per unit time of flight, means for actuating the corresponding arm of the other lever in accordance with the sum of the elevation ballistic and prediction de- 2,577,785 13 14 flections per unit time of flight, means for multi- UNITED STATES PATENTS plying said sums respectively by the time of N b flight to effect displacement of the opposite arms ig f 25 5 5 of the levers respectively in accordance with total 1:481:248 Sperry l Jan 1924 azimuth and elevation deflections comprising 1,730,290 Petschenig et al Oct. 1, 1929 movable fulcrums for the levers both displaced 1 990 577 Watson Feb 12 1935 in accordance time Of flight, l e of Sight 2 01 0 c a t 3 defining means having azimuth and elevation 2O65303 Chafee at 5 1936 line of sight deflecting members, and means for 2125225 Gourdou 1938 actuating said members respectively by c0rre 1 2160202 Fieux May 1939 sponding ones of said opposite arms of the levers. 2164463 July 1939 FLOYD LYON- 2,189,964 Sealey Feb. 13, 1940 2,206,875 Chafee eta1 July 9, 1940 REFERENCES CITED 2,311,187 Murtagn Feb. 16, 1943 The following references are of record in the 1 40 7 Peters 1 2, 194

file of this Patenfl 2,433,843 Hammond et a1 Jan. 6, 194a 

